Interpreting GRB170817A as a giant flare from a jet-less double neutron-star merger

Abstract

We show that the delay between GRB170817A and GW170817 is incompatible with de-beamed emission from an off-axis relativistic jet. The prompt emission and the subsequent radio and X-ray observations can instead be interpreted within a giant-flare-like scenario, being the result of a relativistic outflow driven by the ultra-strong magnetic field produced by magnetohydrodynamic amplification during the merger of the progenitor double neutron-star binary. Within such picture, the data indicate that the outflow must be endowed with a steep velocity profile, with a relatively fast tail extending to Gamma~8. Since the conditions for the launch of such an outflow are quite general, and the presence of a velocity profile is a natural expectation of the acceleration process, most neutron star binary mergers should feature this quasi-isotropic, hard X-ray emission component, that can be a powerful guide to the discovery of additional kilonovae associated to relatively nearby gravitational wave events.

6 pages, 2 figures, accepted by Astronomy and Astrophysics

References in corpus (54)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Multi-messenger Observations of a Binary Neutron Star Merger
• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A
• Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. II. UV, Optical, and Near-IR Light Curves and Comparison to Kilonova Models
• Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger
• INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational Wave Event GW170817
• The X-ray counterpart to the gravitational wave event GW 170817
• A kilonova as the electromagnetic counterpart to a gravitational-wave source
• Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis
• Illuminating Gravitational Waves: A Concordant Picture of Photons from a Neutron Star Merger
• Superluminal motion of a relativistic jet in the neutron star merger GW170817
• Swift and NuSTAR observations of GW170817: detection of a blue kilonova
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. IV. Detection of Near-infrared Signatures of r-process Nucleosynthesis with Gemini-South
• A Radio Counterpart to a Neutron Star Merger
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. III. Optical and UV Spectra of a Blue Kilonova From Fast Polar Ejecta
• The discovery of the electromagnetic counterpart of GW170817: kilonova AT 2017gfo/DLT17ck
• Producing ultra-strong magnetic fields in neutron star mergers
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. V. Rising X-ray Emission from an Off-Axis Jet
• A mildly relativistic wide-angle outflow in the neutron star merger GW170817
• The Binary Neutron Star event LIGO/VIRGO GW170817 a hundred and sixty days after merger: synchrotron emission across the electromagnetic spectrum
• The rate, luminosity function and time delay of non-Collapsar short GRBs
• Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger
• The outflow structure of GW170817 from late time broadband observations
• A Deep Chandra X-ray Study of Neutron Star Coalescence GW170817
• Follow up of GW170817 and its electromagnetic counterpart by Australian-led observing programs
• J-GEM observations of an electromagnetic counterpart to the neutron star merger GW170817
• A Decline in the X-ray through Radio Emission from GW170817 Continues to Support an Off-Axis Structured Jet
• A peculiar low-luminosity short gamma-ray burst from a double neutron star merger progenitor
• The evolution of the X-ray afterglow emission of GW 170817 / GRB 170817A in XMM-Newton observations
• The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817
• A turnover in the radio light curve of GW170817
• Off-axis prompt X-ray transients from the cocoon of short gamma-ray bursts
• The Rapid Reddening and Featureless Optical Spectra of the optical counterpart of GW170817, AT 2017gfo, During the First Four Days
• Off-axis short GRBs from structured jets as counterparts to GW events
• Observations of the first electromagnetic counterpart to a gravitational wave source by the TOROS collaboration
• GRB170817A associated with GW170817: multifrequency observations and modeling of prompt gamma-ray emission
• Short GRBs at the dawn of the gravitational wave era
• Evidence for Cocoon Emission from the Early Light Curve of SSS17a
• A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a
• Optical Follow-up of Gravitational-wave Events with Las Cumbres Observatory
• The gamma-rays that accompanied GW170817 and the observational signature of a magnetic jet breaking out of NS merger ejecta
• GRB 170817A as a jet counterpart to gravitational wave trigger GW 170817
• The Properties of Short gamma-ray burst Jets Triggered by neutron star mergers
• The unpolarized macronova associated with the gravitational wave event GW170817
• Implications of the radio and X-ray emission that followed GW170817
• GRMHD simulations of prompt-collapse neutron star mergers: the absence of jets
• Distance and properties of NGC 4993 as the host galaxy of a gravitational wave source, GW170817
• Constraints from the Time Lag between Gravitational Waves and Gamma Rays: Implications of GW 170817 and GRB 170817A
• Lanthanides or dust in kilonovae: lessons learned from GW170817
• Jet-driven and jet-less fireballs from compact binary mergers
• GRB 170817A: a short GRB seen off-axis
• Constraining the ejecta for the nonthermal emission from GW170817

Cited by in corpus (14)

• First Multimessenger Observations of a Neutron Star Merger
• When Did the Remnant of GW170817 Collapse to a Black Hole?
• THESEUS: a key space mission concept for Multi-Messenger Astrophysics
• 3D magnetised jet break-out from neutron-star binary merger ejecta: afterglow emission from the jet and the ejecta
• The Delay Time of Gravitational Wave -- Gamma-Ray Burst Associations
• A Joint Fermi-GBM and LIGO/Virgo Analysis of Compact Binary Mergers From the First and Second Gravitational-wave Observing Runs
• Magnetically inspired explosive outflows from neutron-star mergers
• Gamma-Ray Bursts with Extended Emission: Classifications, Energy Correlations and Radiation Properties
• Short duration gamma-ray bursts and their outflows in light of GW170817
• How Do Nuclear Isomers Influence the Gamma-Ray Bursts in Binary Neutron Star Mergers?
• Polytropic representation of non-isotropic kinetic pressure tensor for non-ideal plasma fluids in relativistic jets
• A New Search Pipeline for Short Gamma Ray Bursts in Fermi/GBM Data -- A 50% Increase in the Number of Detections
• The Detection Prospect of the Counter Jet Radiation in the Late Afterglow of GRB 170817A
• $\gamma$ rays run on time